Brief Introduction of Permanent Ferrite Magnet

Ferrite magnet is a non-metallic permanent magnetic material developed in the 1940s, composed of Fe2O3, BaO or SrO. Because its preparation process and appearance are very similar to ceramic products, it is sometimes called Ceramic magnet. Compared to metal magnets, Ferrite magnets have lower magnetic energy but are more resistant to demagnetization. Since Ferrite is mainly made of oxides, it is highly resistant to corrosion and oxidation.

Relatively low raw material cost and simple production process make Ferrite magnets occupy the largest market share among all kinds of magnets. As one of the most cost-effective magnetic materials, ferrite magnets are widely used in various industrial applications such as refrigerators, speakers, and small electric motors.

ferrite magnet pdf

Classification of Ferrite (ceramic) magnet

According to different production processes, it can be divided into sintered ferrite magnets and bonded ferrite magnets. Among them, sintered ferrite magnets can be divided into dry pressing and wet pressing, and bonded ferrite magnets are divided into extrusion molding, calendering, and injection molding. Bonded ferrite magnet has softness, elasticity, and distortability. Ferrite magnets provide the lowest magnetic field strength of all permanent magnet materials, with a maximum energy product in the range of 0.8-5.3 MGOe; ferrite magnets are non-conductive and have superior corrosion resistance since they are essentially already made of rust ( Iron oxide), so it will not corrode further. They also maintain performance at high temperatures and can be used at temperatures up to 250 degrees Celsius without any loss of performance.

Ferrite magnets can also be classified as “soft magnets” or “hard magnets”, depending on whether their coercivity is low or high. Ferrite magnets used in transformers or electromagnet cores, containing nickel, zinc or manganese compounds, low coercive force, generally called soft ferrite; ferrite magnets used in permanent magnets are hard ferrite, has higher coercivity and remanence after magnetization. Due to the high coercivity, hard ferrite is not easy to demagnetize, which is also an important characteristic of permanent magnets. Hard ferrite can generate magnetic flux and also has high magnetic permeability.

Performance of Ferrite (Ceramic) Magnets

Different markets use different naming standards. The “Y” nomenclature is the Chinese standard and is the most widely used. Less commonly used are the “C” American nomenclature and the “HF” European standard. The magnetic properties of each standard are comparable. If you are more familiar with US or European standards, you may find the following quick reference guide useful:

Quick reference guide

C1 = Y8T / Y10T

C5 = Feroba 2 = Fer 2 = HF26/18 = Y30

C7 = Y26H-2 C8B = Y33

C8/C8A = Feroba 3 = Fer 3 = Y30H-1

C9 = Y30H-2

C10 = Y33H

C11 = Y34

C12 = Y30H-2

 

Standard Grade RemanenceBr CoercivityHcb IntrinsicCoercivityHcj Max.EnergyProduct(BH)max
mT kG kA/m kOe kA/m kOe kJ/m3 MGOe
Chinese Standard Y8T 200-235 2.0-2.35 125-160 1.57-2.01 210-280 2.64-3.52 6.5-9.5 0.8-1.2
Y10T 200-235 2.0-2.35 128-160 1.61-2.01 210-280 2.64-3.52 6.4-9.6 0.8-1.2
Y20 320-380 3.2-3.8 135-190 1.70-2.39 140-195 1.76-2.45 18.0-22.0 2.3-2.8
Y22H 310-360 3.1-3.6 220-250 2.76-3.14 280-320 3.52-4.02 20.0-24.0 2.5-3.0
Y23 320-370 3.2-3.7 170-190 2.14-2.39 190-230 2.39-2.89 20.0-25.5 2.5-3.2
Y25 360-400 3.6-4.0 135-170 1.70-2.14 140-200 1.76-2.51 22.5-28.0 2.8-3.5
Y26H 360-390 3.6-3.9 220-250 2.76-3.14 225-255 2.83-3.20 23.0-28.0 2.9-3.5
Y26H-1 360-390 3.6-3.9 200-250 2.51-3.14 225-255 2.83-3.20 23.0-28.0 2.9-3.5
Y26H-2 360-380 3.6-3.8 263-288 3.30-3.62 318-350 4.00-4.40 24.0-28.0 3.0-3.5
Y27H 370-400 3.7-4.0 205-250 2.58-3.14 210-255 2.64-3.20 25.0-29.0 3.1-3.6
Y28 370-400 3.7-4.0 175-210 2.20-2.64 180-220 2.26-2.76 26.0-30.0 3.3-3.8
Y28H-1 380-400 3.8-4.0 240-260 3.02-3.27 250-280 3.14-3.52 27.0-30.0 3.4-3.8
Y28H-2 360-380 3.3-3.8 271-295 3.41-3.71 382-405 4.80-5.09 26.0-30.0 3.3-3.8
Y30 370-400 3.7-4.0 175-210 2.20-2.64 180-220 2.26-2.76 26.0-30.0 3.3-3.8
Y30BH 380-390 3.8-3.9 223-235 2.80-2.95 231-245 2.90-3.08 27.0-30.0 3.4-3.8
Y30H-1 380-400 3.8-4.0 230-275 2.89-3.46 235-290 2.95-3.64 27.0-32.0 3.4-4.0
Y30H-2 395-415 3.95-4.15 275-300 3.46-3.77 310-335 3.90-4.21 27.0-32.5 3.4-4.1
Y32 400-420 4.0-4.2 160-190 2.01-2.39 165-195 2.07-2.45 30.0-33.5 3.8-4.2
Y32H-1 400-420 4.0-4.2 190-230 2.39-2.89 230-250 2.89-3.14 31.5-35.0 4.0-4.4
Y32H-2 400-440 4.0-4.4 224-240 2.81-3.02 230-250 2.89-3.14 31.0-34.0 3.9-4.3
Y33 410-430 4.1-4.3 220-250 2.76-3.14 225-255 2.83-3.20 31.5-35.0 4.0-4.4
Y33H 410-430 4.1-4.3 250-270 3.14-3.39 250-275 3.14-3.46 31.5-35.0 4.0-4.4
Y34 420-440 4.2-4.4 200-230 2.51-2.89 205-235 2.58-2.95 32.5-36.0 4.1-4.5
Y35 430-450 4.3-4.5 215-239 2.70-3.00 217-241 2.73-3.03 33.1-38.2 4.2-4.8
Y36 430-450 4.3-4.5 247-271 3.10-3.41 250-274 3.14-3.44 35.1-38.3 4.4-4.8
Y38 440-460 4.4-4.6 285-305 3.58-3.83 294-310 3.69-3.90 36.6-40.6 4.6-5.1
Y40 440-460 4.4-4.6 330-354 4.15-4.45 340-360 4.27-4.52 37.5-41.8 4.7-5.3
American Standard C1 230 2.3 148 1.86 258 3.5 8.36 1.05
C5 380 3.8 191 2.4 199 2.5 27 3.4
C7 340 3.4 258 3.23 318 4 21.9 2.75
C8/C8A 385 3.85 235 2.95 242 3.05 27.8 3.5
C8B 420 4.2 232 2.913 236 2.96 32.8 4.12
C9 380 3.8 280 3.516 320 4.01 26.4 3.32
C10 400 4 280 3.52 284 3.57 30.4 3.82
C11 430 4.3 200 2.512 204 2.56 34.4 4.32
C12 400 4 290 3.65 318 4 32 4
European Standard HF8/22 200/220 2.00/2.20 125/140 1.57/1.76 220/230 2.76/2.89 6.5/6.8 0.8/1.1
HF20/19 320/333 3.20/3.33 170/190 2.14/2.39 190/200 2.39/2.51 20.0/21.0 2.5/2.7
HF20/28 310/325 3.10/3.25 220/230 2.76/2.89 280/290 3.52/3.64 20.0/21.0 2.5/2.7
HF22/30 350/365 3.50/3.65 255/265 3.20/3.33 290/300 3.64/3.77 22.0/23.5 2.8/3.0
HF24/16 350/365 3.50/3.65 155/175 1.95/2.20 160/180 2.01/2.26 24.0/25.5 3.0/3.2
HF24/23 350/365 3.50/3.65 220/230 2.76/2.89 230/240 2.89/3.01 24.0/25.5 3.0/3.2
HF24/35 360/370 3.60/3.70 260/270 3.27/3.39 350/360 4.40/4.52 24.0/25.5 3.0/3.2
HF26/16 370/380 3.70/3.80 155/175 1.95/2.20 160/180 2.01/2.26 26.0/27.0 3.2/3.4
HF26/18 370/380 3.70/3.80 175/185 2.20/2.33 180/190 2.26/2.39 26.0/27.0 3.3/3.4
HF26/24 370/380 3.70/3.80 230/240 2.89/3.01 240/250 3.01/3.14 26.0/27.0 3.3/3.4
HF26/26 370/380 3.70/3.80 230/240 2.89/3.01 260/270 3.27/3.39 26.0/27.0 3.3/3.4
HF26/30 385/395 3.85/3.95 260/270 3.27/3.39 300/310 3.77/3.89 26.0/27.0 3.3/3.4
HF28/26 385/395 3.85/3.95 250/265 3.14/3.33 260/275 3.27/3.45 28.0/30.0 3.5/3.8
HF28/28 385/395 3.85/3.95 260/270 3.27/3.39 280/290 3.50/3.60 28.0/30.0 3.5/3.8
HF30/26 395/405 3.95/4.05 250/260 3.14/3.33 260/270 3.27/3.39 30.0/31.5 3.8/3.9
HF32/17 410/420 4.10/4.20 160/170 2.01/2.14 165/175 2.07/2.20 32.0/33.0 4.0/4.1
HF32/22 410/420 4.10/4.20 215/225 2.70/2.83 220/230 2.76/2.89 32.0/33.0 4.0/4.1
HF32/25 410/420 4.10/4.20 240/250 3.01/3.14 250/260 3.14/3.27 32.0/33.0 4.0/4.1

Advantages & Disadvantages of Ferrite Magnets

Advantages:

Do not corrode in water;

can be used up to +250°C (482°F);

sometimes up to +300°C (572°F) in special circumstances;

high coercivity (Hci) that increases as magnet heats up;

electrically insulating;

relatively low cost – good for cost saving projects.

Disadvantages:

Not as strong as  Neodymium Rare Earth Magnets – typically offering around 1/7th the pull force of similarly sized NdFeB;

specialized shapes can carry tooling charges;

when taken to around -20°C (-4°F) and colder, the Intrinsic coercivity (Hcj) falls to a level that risks the magnet possibly starting to demagnetize (depending on the shape and the application).

 

Development Trend & Market Demand of Ferrite magnet

The rapid growth of DC motors further drives the development trend of permanent ferrite magnet

With the vigorous promotion of energy conservation and environmental protection, the country stipulates that motors with an energy efficiency rating of 3 or lower will be banned from sale since July 1, 2011. Compared with AC motors of the same power, the energy consumption of DC motors is about 30%-50% lower, which is the most direct substitute for AC motors currently in large-scale applications. In the process of replacing AC motors with DC motors, the market demand for permanent ferrite magnets will grow rapidly. AC motors hardly need permanent ferrite magnets, while permanent ferrite magnets are essential and key components in DC motors. A DC motor has at least two pieces of permanent ferrite magnets are required, and as many as dozens of pieces can be achieved. Many home appliance manufacturers such as Samsung, Panasonic, Daikin, Midea and Joyoung are now producing and selling washing machines, air conditioners and other small appliances equipped with DC motors.

Market demand of permanent ferrite magnet industry

Permanent ferrite magnet is mainly used in pillar industries and emerging industries such as automobiles, computers and office equipment, household appliances, electric tools, electric toys, and electroacoustics. At present, the production center of permanent magnet ferrite in the world has shifted to China. According to the data from the Ministry of Information Industry, the output of permanent magnet ferrite in my country was 350,000 tons in 2005, accounting for about 50% of the global output. With the continuous stable and rapid development of my country’s economy, driven by factors such as consumption upgrading, the output and demand of permanent magnet ferrite will continue to grow. It is estimated that the market demand of my country’s permanent magnet ferrite industry in 2012 will be 776,100 tons, and the market capacity will be 10.7 billion RMB.